1. Technical Field
The present disclosure relates generally to surgical instruments and, more particularly, to a surgical instrument for forming a hole in a blood vessel wall.
2. Background of Related Art
In cardiac surgery, it is often necessary to connect a prepared vein to a coronary artery to bypass a diseased area or areas of the artery. Typically, the prepared vein is attached about an opening formed in, for example, the ascending aorta, and then anastomosed to the aorta. In the past, the opening had been formed with the use of a scalpel instrument or scissor instrument. However, aortic punch instruments or perforators have been utilized to create the opening in the vessel wall.
U.S. Pat. No. 4,018,228 to Goosen discloses a surgical punch apparatus including an elongate hollow sleeve and an elongated rod extending through one end of the sleeve and reciprocally moveable therein. The elongated rod has a distal narrowed end portion including a fixed cylindrical blade while the hollow sleeve has a hollow cylindrical blade removably attached thereto. The elongated rod is activated by a handle which pulls the rod and blade into the hollow sleeve thereby forming an opening in the vessel tissue disposed therebetween.
U.S. Pat. No. 4,216,776 to Downie et al. discloses a similar device including an elongated stem and a coaxial disc having an exterior circumferential disc surface separated from the rest of the stem. An elongated tube is mounted on the stem and is slidable thereon to telescope over the coaxial disc. The elongated tube and exterior disc are devoid of sharp cutting edges, but, are dimensioned such that an annular clearance is defined therebetween. The effect of this clearance is that the tissue disposed between the tube and disc is separated by a tensional force instead of cutting or shearing of the tissue.
While the above-devices described in the Goosen '228 patent and the Downie '776 patent are well known, it is desirous to provide an apparatus with improved characteristics and which can provide, through a clean shearing action, a non-circular, preferably, generally racetrack-shaped opening in the blood vessel wall. A racetrack-shaped opening is particularly advantageous when using an anastomosis instrument during for example, a coronary artery bypass grafting (CABG) procedure. In particular, it has been found that the racetrack configuration assists in everting of the blood vessel to appropriately position the vessel wall portions adjacent the opening with respect to the apparatus for firing of the anastomosis clips or staples. In addition, since the vein graft is typically attached to the aorta at an angle less than 90 degrees, e.g., 45 degrees, because the end of the graft is cut at an angle, the racetrack configuration more closely conforms to the shape of the cut end.